Manufacture and treatment of artificial products of cellulose derivatives



Patented Mar. 24, 1936 UNITED STATES MANUFACTURE TREATMENT OF ARTL FICIAL PRODUCTS F CELLULOSE DE- RIVATIVE S Henry Dreyfus, London, England No Drawing. Application July 22, 1931, Serial No. 552,420. In Great Britain July 30, 1930 g '10 Claims.

This invention relates to the treatment of artificial filaments, threads, ribbons, films, fabrics or other materials made of or containing cellulose esters or ethers and to the production of artificial filaments, threads, ribbons, films and the like from solutions containing cellulose esters and ethers.

In United States Patent No. 1,709,470 processes are described for the treatment of materials of cellulose acetate in their fully set and finished condition by stretching them beyond their elastic limit in the presence, if desired, of substances that facilitate the stretching, for example acetone, ethyl alcohol, formaldehyde and glycerine, for the purpose of rendering the filaments resistant, to the action of hot or boiling aqueous liquors, as well as for reducing their denier.

Further, according to my United States application S. No. 378,684 filed 16th July, 1929 filaments or threads of cellulose acetate or other organic derivatives of cellulose are stretched while they are travelling, for example continuously with their production, the stretching again being carried out in the presence of a facilitating agent or agents. Suitable agents are aqueous solutions of thiocyanates, such as those of the alkalies, ammonium and alkaline earths, aqueous solutions of zinc chloride, acetic acid, formic acid, lactic acid, diacetone alcohol, methyl or ethyl lactate, acetone, and the like; and monoand di-ethers or esters or ether esters of olefine glycols and polyolefine glycols, for instance the monoand dimethyl and ethyl ethers of ethylene glycol, glycol mono acetate, methyl glycol acetate, dioxane, the mono methyl and ethyl ethers of propylene glycol, and the mono-ethyl ether of diethylene glycol etc.; phenols, formaldehyde, acetaldehyde, mono-, diand triacetins, dichlorethylene, and the like, mineral acids, sulphonic or other organo-mineral acids, or acid esters of mineral acids, or mixtures of these, or solvent mixtures.

I have now found that improved results may be obtained by applying the softening or solvent agents in a concentration insufficient to exert a substantial solvent or softening action on the materials, and subsequently bringing a solvent or softening action into play. This may be effected by concentrating the more or less dilute solvent or softening agent on the materials. The process is capable of improving the properties of the filaments, threads or other materials whether or not stretching is applied, and in fact without stretching the materials, 1. e. by applying the process under no tension or under a slight tension so I vice, for example an orifice preferably supplied as to allow the materials to shrink or under only suflicient tension that they do not shrink, the products acquire a substantially improved extensibility apart from any increase in tenacity.

The present invention, therefore, includes broadly the concentration on the materials of solvents or softening agents until the solvent action of the same is produced. More particularly it is preferred to carry the concentration to such a point that the filaments or other products may be so softened that separate filaments would be capable of coalescence if brought together.

Any of the agents mentioned above may be employed in the present invention or any other agents capable of exerting a solvent or softening action upon cellulose esters or ethers. These agents may be applied to the materials in a relatively dilute state or at least sufficiently dilute that they do not exert a substantial solvent or softening action on the materials before concen- 20 tration. For this purpose they may be mixed with water or any other suitable diluent inert or relatively inert towards the cellulose derivative, for example alcohols, hydrocarbons, ethers and the like. A diluent is preferably selected which is more volatile than the solvent or softener. For instance it may be'ether in the case of acetone, formic acid, acetic acid, dioxane and like volatile solvents or water or alcohol in the case of diacetone alcohol, methyl or ethyl lactate, lactic acid or other relatively high boiling solvent.

The cellulose acetate filaments, threads, ribbons or the like may, for example. be immersed or carried through a bath containing a relatively dilute solution of the solvent or softening agent,

e. g. diacetone alcohol, methyl or ethyl lactate,

lactic acid, dioxane, acetone etc., or the filaments or other products may be sprayed with the solution and the solution subsequently concentrated in any desired manner.

As an alternative means the travelling filaments, threads, or the like may be caused to take up the solution by means of a wick or other dewith the solution under a forced feed, for instance by means of a pump.

As a further alternative the relatively dilute solution of solvent or softening agent may be (see United States Patents Nos; 1,465,994 and 1,467,493 and United States applications S. Nos. 402,785 filed 26th October, 1929 and 418,414 filed 3rdJanuary 1930). In the case of employing the processes described in the last two specifications the softening or solvent agent should not in general be employed in such a high concentration as is indicated in the examples, since at this strength considerable solvent action is already apparent. United States application S. No. 402,785 describes the addition of diacetone alcohol, ethyl lactate or other solvents to the spinning solution itself and subsequently coagulating so that the said solvent is in contact with the filaments in a relatively high concentration. Such a process may also be employed according to the present invention, it being remembered that the diluent of the solvent should be present in sufficient quantity to inhibit substantial solvent action.

Furthermore filaments or other products produced either by wet or dry spinning processes may be carried into a bath containing a dilute solution of the solvent or may be sprayed with or otherwise caused to take up the solution continuously with the production of the products.

The term dilute used in the present description with reference to the solutions of solvent or softening agents applied is not intended to include only low concentrations but to include any concentration of reagent which during the period of application will not have a strong solvent action. The term dilute is thus used for differentiating the solutions applied from the concentrated solutions produced on the fibre by the concentration step and which are capable of exerting a solvent or strong softening action.

In the case of diacetone alcohol, diethyl lactate, lactic acid, diethyl tartrate and the like, it is preferred to apply solutions of below about 40 to concentration and most advantageously below about 25 to 30%. In most cases water is the most convenient diluent, but the invention is by no means limited thereto.

The concentration of the softening or solvent agents on the fibre or material may be effected in any convenient manner. For instance the materials after being impregnated with a more or less dilute solvent or softening agent may be subjected to a treatment so as to evaporate the water or other diluent, for example by heating or by applying a vacuum or by blowing air, nitrogen, carbon dioxide and other inert gases over or through the materials. The-concentration may furthermore be effected at low, ordinary or even high temperatures, whether -efiected at under reduced pressure or not. Diacetone alcohol, ethyl lactate, lactic acid, diethyl tartrate and the like applied for instance at ordinary temperatures in a concentration of about 15 to 25% may be concentrated by the application of reduced pressures and/or increased temperatures to a strength of about to 80% so as to induce the solvent action. Again acetone, applied, for instance in an ethereal solution of about 20 to 40% concentration, may be concentrated up to about to 80% or more. Alternatively the reagents may be concentrated to a point short of that necessary to exert a solvent action, and the solvent action be brought into play simply and solely by raising the temperature. If desired, the temperature may be raisedin two or more stages so as to bring into play a. progressively strong solvent action. As already indicated the invention particularly contemplates the concentration upon the materials of the solvent or softening agents to such an extent that either at ordinary temperatures or at raised temperatures the materials are so softened that if two or more filaments, threads or the like are brought together coalescence takes place. The filaments or other products. may if desired be allowed to coalesce so as to stick together any desired number of individual filaments and produce a relatively large unitary filament orto produce a ribbon or straw-like product by arranging the filaments side by side and causing them to adhere. Alternatively coalescence may be prevented by any suitable means. For instance the filaments or other products during the concentration of the solvent or softening agent thereon and/or during the time it exerts its solvent action may be kept separate, for example by passage over curved guides or other devices adapted to achieve this object. Again during the concentration of the agentsand/or during any heat treatment to which they may be subjected to produce or increase the solvent action of the reagents, the materials may be passed through a liquid whereby they are prevented from adhering to each other, the liquid being such that it exerts substantially no solvent action on the cellulose ester or ether, and at the same time is practically anon-solvent for the particular solvent or softening agent with volatile or no more volatile than the solvent or softening agent. itself, may be applied together with the solvent or softening agent, e. g. in a bath subsequent to or continuously with production or in the coagulating bath or even in the spinning solution. a

The liquids may themselves be the concentrating the softening or solvent agent on the materials and/or the means of raising the temperature if desired to produce the requisite solvent action. For example the materials impregnated with the more or less dilute solvent or softening agent may be passed through a hot liquid bath so as to drive off the water or other liquid diluent. Again if desired the liquid bath,

especially in the case of concentrating the solvent,

or softening agent to a point short of actual solvent power, may be used simply for the purpose of raising the temperature until the required solvent power is produced, and as already indicated the increase in temperature may be brought about in stages so as to obtain a progressive solvent action. Even when using liquids to prevent coalescence of the filaments or other products, curved guides or othermechanical devices adapted to assist in keeping the filaments apart may be used. If desired the bath applied may itself be the means of concentrating the solvent or softening agent on the materials. For example the bath may be so chosen that it is a non-solvent for the cellulose derivative, a non-solvent for the solvent or softening agent and a solvent for the water or other diluent.

After the agents have been concentrated on the materials and have exerted their solvent or softening action they may if desired be removed by simple volatilization, especially when relatively volatile agents are employed, having a boiling point for example between about 50 C. or 100 C. and 200 0., the volatilization being assisted, if desired, by reduced pressure, or as an alternameans of tive they may be removed from the materials by dissolving or washing out.

As described above during the concentration of the solvent or softening agent upon the materials and/or during the period in which the agent exerts its solvent action, the materials may if desired be subjected to a stretch treatment, though it is to be understood that the invention is not confined to stretching. However due to the action of the concentrated solvent or softening agents the materials are in a good condition for stretching so as to produce products of fine denier or relatively low cross-section.

The processes of the present invention are most conveniently applied to the filaments, threads or other products while travelling from point to point, for example while travelling from bobbin to bobbin or from the spinning apparatus to a winding apparatus.

The processes of the invention may be applied broadly to the treatment of materials made of Example 1 Cellulose acetate filaments, while in transit from bobbin to bobbin, are passed through a bath 1 having the following constitution:-

Per cent Ether 50 Dioxane 30 Water 20 After passage through the bath the filaments carrying a large bulk of the liquor are given an air passage so as to cause the evaporation of the ether from the filaments leaving the aqueous dioxane thereon. This may be effected in the open air, but is preferably carried out in an enclosed or substantially enclosed chamber so that the ether may be recovered. Hot or warm air may be passed through the chamber so as to facilitate the evaporation of the ether, or alternatively the threads may be passed over a warm plate maintained, for instance, at a temperature of 40 to 50 C. During the concentration of the dioxane on the filaments, the latter may be kept apart, as for example by passage over curved guides, or alternatively the filaments may be coalesced to form a monofil, or may be arranged in a line so as to coalesce and form a ribbon type of product. In the latter case the adhesion may be improved by passage between'rollers. If desired, the dioxane may be removed from the filaments, monofil or ribbon, or if a stretching is required the material may be subjected to the stretching operation continuously with the concentration of the dioxane thereon. Thus for instance after the evaporation of the ether, and preferably after the dioxane has been allowed to act for a short time, the filaments may be passed continuously round two rollers having different peripheral speeds. By this means the filaments may be stretched, for instance to an extent of 30 to 7 0, or even of their original length. The dioxane may thereafter be removed from the filaments by any desired means, as for instance by treating them with a salt solution, as described in United States application S. No. 399,384 filed 12th October, 1929, or by first treating them with a 20% solution of dioxane followed by a. treatment with water. Such washing operations may be conducted in a centrifugal spinning box in which the filaments may be received.

Example 2 Filaments of cellulose acetate, travelling from bobbin to bobbin or from a bobbin to any other packaging device, are carried through a bath consisting of a 20% to 25% aqueous solution of lactic acid. The filaments carrying the liquor are then passed into a bath containing a petroleum fraction boiling at 250 to 300 C., and maintained at a temperature of to C. By this means the lactic acid is concentrated on the filaments, the water being evaporated and the petroleum hydrocarbon serving to keep the filaments apart. The filaments may thereafter be stretched or not as desired, and the lactic acid removed therefrom, as described in Example 1. r

Instead of impregnating the already formed filaments with the 20% to 25% lactic acid, such impregnation may take place in the course of their production by a wet spinning process, as described for example in United States application S. No. 402,785. Alternatively, if desired, the impregnation may take placecontinuously with the production of the filaments by a dry spinning process.

What I claim and desire to secure by Letters Patent is:-

1. Process for the treatment of filaments.

threads, ribbons, films and other materials containing cellulose esters or ethers, which comprises treating the same with a liquid medium containing a reagent having a solvent or softening action upon the cellulose derivative in a concentration insufficient to exert a solvent or softening action, and thereafter treating the liquid medium with an agent to increase the concentration of the reagent on the materials in order to bring the solvent or softening action into play, whereby the physical properties of the materials are improved.

2. Process for the treatment of filaments, threads, ribbons, films and other materials containing cellulose esters or ethers, which comprises treating the same with a liquid medium containing a solvent or softening agent for the cellulose derivative together with a non-solvent diluent of higher volatility than the said agent, which liquid medium iswithout solvent or softening effect on the cellulose derivative, and thereafter concentrating the solvent or softening agent on the materials by evaporating at least a part of the non-solvent diluent so as to bring the solvent or softening action of the agentinto play, whereby the physical properties of the materials are improved.

3. Process for the treatment of filaments,

threads, yarns and other textile materials containing cellulose esters or ethers, which comprises treating the same with a liquid medium containing a solvent or softening agent for the cellulose derivative together with a. non-solvent diluent of higher volatility than the said agent, which liquid heat to assist the solvent or softening action, 'whereby the serimetric properties of the materials are improved.

4. Process for the treatment of filaments, threads, and other textile materials containing cellulose esters or ethers, which comprises treating the same with a liquid medium containing a solvent or softening agent for the cellulose derivative together with a non-solvent diluent of higher volatility than thesaid agent, which liquid medium is without solvent or softening effect on the cellulose derivative, and thereafter passing the materials under conditions in which they are free to shrink through a heated inert liquid so as to concentrate the solvent or softening agent on the materials by evaporation of at least a part of the non-solvent diluent, whereby the extensibility of the materials is improved.

a 6. Process for the treatment of ,filaments, threads, and other textile materials containing cellulose acetate, which comprises treating the same with a liquid medium containing a solvent or softening agent for the cellulose acetate together with a non-solvent diluent of higher volatility than the said agent, which liquid medium 4 6. Process for the treatment of filaments,-

threads, and other textile materials containing cellulose esters or ethers, which comprises treating the same with a liquid medium containinga solvent; or softening agent for the cellulose derivative together with a non-solvent diluent of higher volatility than the said agent, which liquid mediumis without solvent or softening eifect on the cellulose derivative, thereafter passing the materials through a heated inert liquid so as to concentrate the solvent or softening agent on the materials by evaporation of at least a. part of the non solvent diluent, and stretching the materials, whereby the tenacity of the materials is improved.

7. Process for the treatment of filaments, threads, and other textile materials containing cellulose acetate, which comprises treating the same with a liquid medium containing a solvent or softening agent for the cellulose derivative together with a non-solvent diluent of higher volatility than the said agent, which liquid medium is without solvent or softening effect on the cellulose derivative, thereafter passing the materials through a heated inert liquid so as to concentrate the solvent or softening agent on the materials by evaporation of at least a part of the non-solvent diluent, and stretching the materials, wherethreads, and other textile materials containing cellulose esters or others, which comprises treating the same with a-liquid medium containing a solvent or softening agent for the cellulose derivative together with a non-solvent diluent of higher volatility than the said agent, which liquid medium is without solvent or softening effect on the cellulose derivative, and thereafter concentrating the solvent or softening agent on the materials by evaporating at least a part of the nonsolvent diluent so as to bring the solvent or softening action of the agent into play and thus soften the materials to a point at which the individual filaments or other materials are capable of coalescence, whereby the serimetric properties of the materials are improved.

9. Process according to claim 'I wherein the materials are maintained separate from one another so as to prevent coalescence.

10. Process according to claim 7, wherein the materials are brought into contact with one another so that they coalesce.

HENRY DR-EYF'US. 

